How to use

com.facebook.presto.sql.tree.IfExpression

constructor

@Override
protected Object visitIfExpression(IfExpression node, Object context)
{
  Object trueValue = processWithExceptionHandling(node.getTrueValue(), context);
  Object falseValue = processWithExceptionHandling(node.getFalseValue().orElse(null), context);
  Object condition = processWithExceptionHandling(node.getCondition(), context);
  if (condition instanceof Expression) {
    Expression falseValueExpression = (falseValue == null) ? null : toExpression(falseValue, type(node.getFalseValue().get()));
    return new IfExpression(
        toExpression(condition, type(node.getCondition())),
        toExpression(trueValue, type(node.getTrueValue())),
        falseValueExpression);
  }
  else if (Boolean.TRUE.equals(condition)) {
    return trueValue;
  }
  else {
    return falseValue;
  }
}

  private static IfExpression createIfExpression(Expression left, Expression right, ComparisonExpression.Operator operator, Expression result, Type trueValueType)
  {
    return new IfExpression(
        new ComparisonExpression(operator, left, right),
        result,
        new Cast(new NullLiteral(), trueValueType.getTypeSignature().toString()));
  }
}

return new IfExpression(
    getLocation(context),
    (Expression) visit(context.expression(0)),

@Test
public void testIf()
{
  assertExpression("if(true, 1, 0)", new IfExpression(new BooleanLiteral("true"), new LongLiteral("1"), new LongLiteral("0")));
  assertExpression("if(true, 3, null)", new IfExpression(new BooleanLiteral("true"), new LongLiteral("3"), new NullLiteral()));
  assertExpression("if(false, null, 4)", new IfExpression(new BooleanLiteral("false"), new NullLiteral(), new LongLiteral("4")));
  assertExpression("if(false, null, null)", new IfExpression(new BooleanLiteral("false"), new NullLiteral(), new NullLiteral()));
  assertExpression("if(true, 3)", new IfExpression(new BooleanLiteral("true"), new LongLiteral("3"), null));
  assertInvalidExpression("IF(true)", "Invalid number of arguments for 'if' function");
  assertInvalidExpression("IF(true, 1, 0) FILTER (WHERE true)", "FILTER not valid for 'if' function");
  assertInvalidExpression("IF(true, 1, 0) OVER()", "OVER clause not valid for 'if' function");
}

@Test
public void testExpressionsThatMayReturnNullOnNonNullInput()
{
  List<Expression> candidates = ImmutableList.of(
      new Cast(nameReference("b"), "BIGINT", true), // try_cast
      new FunctionCall(QualifiedName.of("try"), ImmutableList.of(nameReference("b"))),
      new NullIfExpression(nameReference("b"), number(1)),
      new IfExpression(nameReference("b"), number(1), new NullLiteral()),
      new DereferenceExpression(nameReference("b"), identifier("x")),
      new InPredicate(nameReference("b"), new InListExpression(ImmutableList.of(new NullLiteral()))),
      new SearchedCaseExpression(ImmutableList.of(new WhenClause(new IsNotNullPredicate(nameReference("b")), new NullLiteral())), Optional.empty()),
      new SimpleCaseExpression(nameReference("b"), ImmutableList.of(new WhenClause(number(1), new NullLiteral())), Optional.empty()),
      new SubscriptExpression(new ArrayConstructor(ImmutableList.of(new NullLiteral())), nameReference("b")));
  for (Expression candidate : candidates) {
    EqualityInference.Builder builder = new EqualityInference.Builder();
    builder.extractInferenceCandidates(equals(nameReference("b"), nameReference("x")));
    builder.extractInferenceCandidates(equals(nameReference("a"), candidate));
    EqualityInference inference = builder.build();
    List<Expression> equalities = inference.generateEqualitiesPartitionedBy(matchesSymbols("b")).getScopeStraddlingEqualities();
    assertEquals(equalities.size(), 1);
    assertTrue(equalities.get(0).equals(equals(nameReference("x"), nameReference("b"))) || equalities.get(0).equals(equals(nameReference("b"), nameReference("x"))));
  }
}

return new IfExpression(
    getLocation(context),
    (Expression) visit(context.expression(0)),

return new IfExpression(
    getLocation(context),
    (Expression) visit(context.expression(0)),

@Test
public void testIf()
{
  assertExpression("if(true, 1, 0)", new IfExpression(new BooleanLiteral("true"), new LongLiteral("1"), new LongLiteral("0")));
  assertExpression("if(true, 3, null)", new IfExpression(new BooleanLiteral("true"), new LongLiteral("3"), new NullLiteral()));
  assertExpression("if(false, null, 4)", new IfExpression(new BooleanLiteral("false"), new NullLiteral(), new LongLiteral("4")));
  assertExpression("if(false, null, null)", new IfExpression(new BooleanLiteral("false"), new NullLiteral(), new NullLiteral()));
  assertExpression("if(true, 3)", new IfExpression(new BooleanLiteral("true"), new LongLiteral("3"), null));
  assertInvalidExpression("IF(true)", "Invalid number of arguments for 'if' function");
  assertInvalidExpression("IF(true, 1, 0) FILTER (WHERE true)", "FILTER not valid for 'if' function");
  assertInvalidExpression("IF(true, 1, 0) OVER()", "OVER clause not valid for 'if' function");
}